<!DOCTYPE html>
<html>
<head>
<style>
.btn-group .button {
  background-color: #4CAF50; /* 绿色 */
  border: 5px solid black;
  color: white;
  padding: 15px 32px;
  text-align: center;
  text-decoration: none;
  font-size: 16px;
  cursor: pointer;
  width: 150px;
  display: block;
  /* display: inline-block; */
}

/* .btn-group .button:not(:last-child) {
  border-bottom: none;   阻止双边框 
} */

.btn-group .button:not(:first-child) {
  border-top: none; /* 阻止双边框 */
} 

.btn-group .button:hover {
  background-color: #3e8e41;
}
</style>
</head>
<body>

<h1>垂直按钮分组</h1>

<div class="btn-group">
  <button class="button">Button</button>
  <button class="button">Button</button>
  <button class="button">Button</button>
  <button class="button">Button</button>
</div>

</body>
</html>
